Well drilling



D- B. GRABLE Nov. 9, 1965 WELL DRILLING 2 Sheets-Sheet 1 Filed March 10 1961 lliull f A h'lln l llllmwllllllllihwlw l l mfimflfl nalail.

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ATTORNEYS D. B. GRABLE WELL DRILLING Nov. 9, 1965 2 Sheets$heet 2 Filed March 10 1961 Do/vo vn/v B. GRFIBLE ATTOIZNEYS United States Patent ship Filed Mar. 10, 1961, Ser. No. 94,917 8 Claims. '(Cl. 175--71) This invention has to do with improved methods and equipment for the drilling of oil or water wells, and has for its general object to provide in a novel and practical manner for utilizing essentially a single facility for both supporting the formation as drilling proceeds, and conducting cutting-entraining fluid into and out of the well, all in conjunction with a type of drilling that assures reduction of the formation to entrainable fineness.

In accordance with the invention, I run into the well a pipe string assembly comprising inner and outer pipes annularly spaced to provide a fluid passage between them and having an outlet at the bottom of the string, the latter being externally sized so as to aiford continuous support for the bore side wall formation as drilling proceeds. As will appear, fluid discharged from said passage into the bottom of the hole, is utilized to entrain and carry drill cuttings up through the inner pipe to the ground surface.

The invention is further and particularly concerned with employment of a type of drilling that will effect reduction of the formation to cuttings of such powdery consistency as will assure their entrainability and removal from the well in the circulating fluid stream. For this purpose, I preferably employ the well known cable drilling, or pneumatic drilling, using a tool having vertically reciprocable action that effectively cuts and powders the formation. As will appear, the same tool, or type of tool, may be used to ream the formation to the full diameter of the pipe string sleeve, thus permitting pro gressive lowering of the string as drilling proceeds.

With drilling working in conjunction with the functions of the dual pipe string, drilling may occur without interference by cave-ins because of the supporting effect of the pipe string, and interference by fluid intrusions into the well is minimized by the close association of the pipe string with the formation.

After completion of the well, the concentric pipe string ordinarily will be moved and replaced by tubular casing sized in conformance with the bore diameter.

All features and objects of the invention, as well as the details of an illustrative embodiment, will be more clearly understood from the following detailed description of the accompanying drawing, in which:

FIG. 1 is a general view showing the equipment assemblage in a well;

FIG. 2 is an enlarged view taken in cross section through the bottom extent of the dual pipe string;

FIG. 3 is an enlarged fragmentary showing of the casing shoe and its relation to the formation; and

FIG. 4 is a view similar to FIG. 2 illustrating the use of a pneumatic drilling and reaming tool.

Referring first to the general illustration of FIG. 1., the well bore is shown to receive the concentric pipe string generally indicated at 11, which may be lowered as required and in keeping with the drilling progress, by any suitable means such as the diagrammatically indicated elevator 12 operating in the derrick 13. Operating within and below the pipe string 11 is a conventional string of cable drilling and reaming tools, generally indicated at 14, reciprocable vertically by cable 15 extending through appropriate packing at 16 in the pipe string head 17. During drilling and reaming, the cable 15 is raised and lowered by conventional ground surface equipment, not shown.

The string 11 is shown to comprise inner and outer pipes 18 and 19 annularly spaced at 20 to provide a passage for reception of high velocity fluid discharged by pump or compressor 21 through line 22 communicating with the passage 20. Desirably, the cutting-entraining fluid is com-pressed air, and consequently the displacement means 21 preferably will be one or more air compressors discharging air into passage 20 at several hundred pounds psi. The outer string of pipe 19 is made up of sections interconnected by threaded flush joints at 24, and the inner string of pipe 18 is similarly made up of threaded flush joints at 25, the joints at corresponding ends of the interconnected stands having such correspondence in their thread formation as to permit simultaneous screwing together of the inner and outer pipes. The latter may be interconnected in any suitable manner to leave an essentially annular passage 20, as by circularly spaced lugs 26 welded or otherwise secured to the pipes.

At its lower end, the pipe string 11 carries a shoe 27, see FIG. 3, having screw thread connections at 28 and 29, respectively, with pipes 19 and 18, the lower end of the annular passage 20 communicating with orts or passages 30 extending through the shoe 27 at circularly and uniformly distributed locations within the shoe. Passages 30 open through the inner annular and outwardly inclined face 31 of the shoe terminating at the bottom of a radial enlargement 32 of somewhat greater diameter than surface 33 and pipe 19.

The cable tool string 13 may comprise the usual series of a rope socket 34, jar 35, stem 36 and bit 37. The bit is shown diagrammatically to be of a known type carrying radially projecting reamer blades 38 which are expansible to the FIG. 1 position by bottoming of the tool in the hole from a condition of the bit in which the reamer blades are radially contracted as in FIG. 2.

In considering the drilling operation, assume the pipe string and cable tools to be positioned in the well as in FIG. 2. Vertical reciprocation of the cable tool string cuses the bit 37 to have cutting impact against the bottom of the hole, and also a pounding or hammering action which, characteristically reduces the cutting to powdery consistency. Simultaneously with the drilling, compressed air is discharged down through passage 20 to be jetted inwardly from passages 30 in the direct region of operation of the bit, so as to entrain the powdery cuttings and conduct them upwardly through passage 40 inside pipe 18, within which the compressed air stream has high velocity return flow to the ground surfaces, where the entrained cuttings may be conducted to suitable disposal as through pipe 41, communicating with passage 40.

During downward advancement of a hole, the pipe string 11 may be progressively lowered to give such continued support to the side formation of the hole 10 as may be desired. Usually it will be possible to maintain the shoe 27 in close proximity to the bottom of the hole during normal drilling. At intervals the tool 37 may be operated to underream the shoe 32, for which purposes spacing may be maintained between the shoe and bottom of the hole a distance at least as great as the tool stroke with the reamer blades 38 expanded, thus allowing the latter to enlarge the hole substantially as shown in FIG. 1. Following reaming, the pipe string may be brought down to the FIG. 3 condition where the bottom discharge ends of the passages 30 are brought to such proximity to the bottom of the hole as to cause the jetted air streams to effectively sweep across the bottom of the hole and entrain the powdery cuttings as rapidly as they are formed.

After the well is drilled to the desired depth, the cable tool string and pipe string 11 may be removed from the well, and the pipe string replaced by a conventional tubular casing sized in supporting conformance with the well bore.

FIGv 4 illustrates a variational embodiment of the invention similar in all respects to FIG. 3 as to structure, function and mode of operation of the concentric pipe string 11, but differing in the type of drilling and reaming tool employed. Here, instead of using the described conventional cable tool drill and reamer assembly, I may use any of various known pneumatically actuated drills such as I have generally indicated at 45, comprising a bit 46 given rapid vertical reciprocation and hammering impact against the bottom hole formation, by an actuator or motor section 47. Compressed air or other gas is delivered to the tool by a suitable conduit such as drill pipe 48 running to the ground surface and connected to the compressor. The Mission Manufacturing Co. HAM- MERDRIL is illustrative of known kinds of pneumatically actuated drills suitable for purposes of the invention. Also it may be mentioned that the invention contemplates broadly the use of any kind of drill having the capacity for reducing the formation to such fineness as to insure entrainment of the cuttings in the circulated air stream. As in the case of the cable tool, the bit 46 may also comprise suitably mounted reamer blades 48 initially held in contracted position :by an encircling wire 49 which can be broken by impact of the tool against the bottom formation to allow expansion of the blades under the influence of springs 50 to the dotted line positions indicated at 51. The tool thus becomes adapted for both pneumatic drilling and undercutting of the surrounding pipe string. In hammerdrilling operations, there may arise circumstances where more air is needed to flush the hole and entrain the bit cuttings, than can be put through the drill air feed conduit, so that the bit penetration rate is undesirably slowed. Also in hammerdrilling, more air flow against the formation may be needed in sticky drilling than is available through the normal air feed conduit. The invention effectively supplements any such deficiencies in the air feed to the hammerdrill, by providing for independent air delivery at whatever rates required, through the injection passage 47.

Another advantage of the invention is that it permits introduction in a novel manner in relation to the cutting tool or hit, of any of various additives which may act either upon the formation to increase the drilling efficiency or improve the entrainability of cuttings or liquid intrusions into the bottom hole area. For such purposes, I may introduce with the injected air stream through passages 20 or 47, any of the commonly used liquid formation treating reagents or materials, or entrainment aids, such as any of the commonly used foaming agents, the effect of which is to increase the liquid or solid particle entrainment rates in the circulated air stream.

I claim:

1. In a Well bore, the combination comprising a pipe string engaging and supporting the Wall of the bore and adapted to be progressively lowered therein, said string including annularly spaced inner and outer pipes defining between them a fluid injection passage having an outlet at the bottom of the string, a tool, means for running said tool down through said inner pipe and operable to drill the bore and reduce the bottom formation to powdery consistency, and means for discharging fluid at high velocity downwardly through said passage, inwardly through ports closely adjacent the tool and thence into the bottom of the bore to sweep across said bottom and entrain the tool cuttings and carry them upwardly through said inner pipe to the ground surface.

2. The combination of claim 1, in which the last mentioned means includes a compressor operating to discharge air through said passage and outlet.

3. The combination of claim 1, including a shoe to which said pipes are connected, said outlet extending through said shoe.

4. The combination of claim 1, including a shoe which has a diameter larger than the outside diameter of said outer pipe, and said tool includes means operable to ream the well bore to the full diameter of the shoe. 5. The combination of claim 4, in which said means for discharging fluid at high velocity downwardly to said passage includes a compressor operating to discharge air through said passage and outlet.

6. The combination of claim 1, including a cable run down through said inner pipe, said cable operably carrying said tool for actuation of said tool.

7. The combination of claim 1, in which said tool includes means actuated by compressed air delivered through said inner pipe for effecting the drilling operation.

8. The method that includes, lowering in a well bore a pipe string including annularly spaced inner and outer pipes defining between them a fluid injection passage having an outlet at the bottom of the string, drilling the central bottom of the hole independently of said string and reducing the drilled formation to powdery consistency, progressively supporting the side wall formation of the bore by said pipe string, and circulating high velocity compressed air through said passage into the bottom of the bore, jetting said compressed air to flow inwardly in the reach of operation of an operating drill bit at the hole bottom so as to sweep across the bottom of the hole to entrain and remove cuttings through the inner pipe of the pipe string to the ground surface.

References Cited by the Examiner UNITED STATES PATENTS 563,106 6/96 Washington -171 597,316 1/98 Durbrow 175215 701,547 6/02 Davis 175171 992,527 5/11 Wigle 175--171 1,512,140 10/24 Schaub 175-67 X 2,019,719 1 1/35 Miller 175205 2,033,527 3/36 Kitching 17592 2,292,126 8/42 Isley 175171 2,684,229 7/54 Bergstrom 175-171 X Y 2,786,652 3/57 Wells 175171 X 2,950,087 8/60 Gregory 175-205 X CHARLES E. OCONNELL, Primary Examiner.

BENJAMIN BENDETT, BENJAMIN HERSH,

Examiners. 

8. THE METHOD THAT INCLUDES, LOWERING IN A WELL BORE A PIPE STRING INCLUDING ANNULARLY SPACED INNER AND OUTER PIPES DEFINING BETWEEN THEM A FLUD INJECTION PASSAGE HAVING AN OUTLET AT THE BOTTOM OF THE STRING, DRILLING THE CENTRAL BOTTOM OF THE HOLE INDEPENDENTLY OF SAID STRING AND REDUCING THE DRILLED FORMATION TO POWDERY CONSISTENCY, PROGRESSIVELY SUPPORTING THE SIDE WALL FORMATION OF THE BORE BY SAID PIPE STRING, AND CIRCULATING HIGH VELOCITY COMPRESSED AIR THROUGH SAID PASSAGE INTO THE BOTTOM OF THE BORE, JETTING SAID COMPRESSED AIR TO FLOW INWARDLY IN THE REACH OF OPERATION OF AN OPERATING DRILL BIT AT THE HOLE BOTTOM SO AS TO SWEEP ACROSS THE BOTTOM OF THE HOLE TO ENTRAIN AND REMOVE CUTTINGS THROUGH THE INNER PIPE OF THE PIPE STRING TO THE GROUND SURFACE. 